Thank you for your help it's very much appreciated.

Tom Robinson

-----Original Message-----
From: Rene Tschaggelar [mailto:[EMAIL PROTECTED]
Sent: Monday, October 25, 2004 3:57 PM
To: Protel EDA Discussion List
Subject: Re: [PEDA] Need some help...Conducted RF immunity test...


Tom Robinson wrote:

> We are currently attempting to get all our products to meet the new
> requirements for the EN60601-1-2-2001 by the November 1st deadline. We
have
> all our products updated to the new requirements except for one. We have
> been having some difficulty with the new Conducted RF immunity test
> EN61000-4-6 / ENV50141 on this product. This test basically takes an AM
> modulated signal with a 3V level in the range of 150k to 80 meg and
couples
> it into all I/O and power cables using a bulk current injection probe
clamp.
> Our system is detecting the induced interference and shutting down
> indicating a fault condition exists. Unfortunately this is considered a
> failure for this test. Has anyone had any experience trying to comply to
> this test. We have tried filtering several critical signals to prevent the
> faults, but the induced signal seems to everywhere. Any suggestions would
be
> helpful at this point.

Yes, the conducted RF...
Do you have a metal enclosure ? If so, it has to be grouded.
Is your PCB also connected to the case ?
Even a slow analog or digital pcb requires an RF layout, or
at least partially.

To make it simple I tell you how to pass this test.
1)have a blank metal case with the pcb inside and the
   case connected to earth
2)the GND of the pcb is at least AC connected to the case, eg
   with 100nF every few cm. Better, if the GND and the case are
   conneted at one point, usually where the supply comes in, or
   the GND is connected to the case at the circumference.
   That depends whether the pcb is analog, digital or RF.
3)each wire coming into the case is connected to the case with
   a 100nF for slow signals and 10nF for faster signals. These
   caps short the RF. Consider the RF may go to 3GHz in the
   actual version, so keep the connections short. One inch is a
   lambda quarter antenna and the case may act as resonator.

Ah, you have a plastic case, that makes it more complicated.
You are a bit late with a 1. Nov deadline...

Rene



 
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